Unit8 情態動詞和助動詞
一、考點聚焦
1、 情態動詞的基本用法
(1)can、be able to 和could
①can和be able to都表示能力,意思上沒多大區別。但can只有現在和過去時,而be able to則有更多的形式。但當成功地完成某一具體動作時,通常不用could而用was/were able to來表示。這時was/were able to 相當於managed to,表示經過一番努力,終於能夠完成某事。如:
Can you use chopsticks?
The wounded man still was able to get to the village and was saved in the
end.
②can和could
can和could都可以表示能力、技能、許可、建議或請求和可能性。但比較委婉客氣地提出問題或陳述看法,一般用could,回答時則用can。如:
Could you help me carry the bag?
Can I help you?
(2)may/might
①may/might表示可能,但may比might可能性大。如:-Why isn’t he in class?
He may be sick.(生病的可能性較大)
-
He might be sick.(生病的可能性較小)
②may/might表示“允許”,may用於現在時或將來時,might常用在間接引語中表過去時,但might也可用於現在時間,表示比較委婉的語氣,回答用may。如:
He says we may leave.
He said we might leave.
③may / might 表示建議或請求,但might比may 更客氣,意思更肯定而無過去時態的含義。
Yes, you can / may.
-May / Might I use your bike? -
No, you mustn’t
(3)must
①must表示必須,應該,沒有時態變化。如:
You must do everything as I do.
②must表示肯定的推測。如:
The light is still on, so he must be at home.
③mustn’t 表示禁止做某事。如:
You mustn’t smoke in the office.
(4)have to
have to 表示“必須、不得不”,是由於某種外界(客觀)原因而“必須”,“不得不”做某事,也可表示經常的或習慣性的事“必須”做。have to的否定形式表示不必。have to可用於多種時態中。如:
You will have to clean your own boots when you join the army.
I have to be at my office every evening.
(5)should / ought to
①should和ought to表示應當、應該,前者比後者語氣輕。如:
You should / ought to work hard.
②should / ought to work hard.
Since she is not here, whe should / ought to be in the classroom.
③should / ought to的否定形式表示禁止之意。如:
Children shouldn’t smoke.
④should可表示陳述意見,推出建議或請求;而ought to可以表示勸告之意。如:
You ought to respect your parents.
He suggested that they should leave at once.
(6)will / would
①will 用於各種人稱表示“意志”、“意願”或“決心”等,否定式won’t + 動詞。如:
I will tell you all about it.
Tom won’t do such a thing.
②will用於疑問句中,常用在第二稱時表示説話人向對方提出“請求”或“詢問”如:
Will you please tell her the news when you see her?
③will 表示習慣性的動作,有“總是”、“慣於”的含義。如:
Fish will die out of water.
④would 表示客氣的請求、建議或意願。如:
Would you please be quiet?
Would you like coffee?
⑤would 表示過去反覆發生的動作。如:
When I passed my school I would see my teachers who taught me 5 years ago.
(7)need
need 作“必要”講,既可作情態動詞,也可作實義動詞。作實義動詞時後面的動詞不定式要帶to,其變化與一般動詞相同。如:
I need to think it over.
-Need you go now? -Yes, I must./No, I needn’t
(8)dare
dare表示“敢”的意思。作為情態動詞時,主要用在疑問句和否定句中。dare若作實義動詞,後面可帶to的不定式,此時to也可以省略。dare與need的用法相似。如:
How dare you say that?
She doesn’t date(to)ask her father.
(9)used to
used to表示過去常常發生的動作或存在的習慣,但現在已不復存在了。如:
He used to smoke.
(10)shall
①shall作為情態動詞用於第二、三人稱,表示説話人的意願,有“命令”、“警告、威脅、強制”和“允許”等意思。如:
We shall do as our teacher says.
You shall have the book as soon as I finish it.
②在疑問句中,shall用於徵求對方的意見或請求指示,常用於第一、第三人稱。如:
Where shall he wait for us?
Shall we go out for a walk?
2、情態動詞表示推測或判斷的用法
下表即是表示推測的情態動詞使用的場合:
情態動詞 對現在和未來的推測 對過去的推測 使 用 場 合
must must + 動詞原形 must have done 肯定句
may / might may / might + 動詞原形 May / might have done 肯定句、否定句
can /could can / could do Can / could have done 否定句、疑問名(could可用於肯定句)
should 用來表示一種估計的情況“按理會/估計會”should do/be should have done 肯定句、否定句、疑問句
例如:
It must have rained last night.
She may not be at home. = It is possible that she is not at home.
She can’t be at home. = It is impossible that she is at home.
They should be there right now.
3、情態動詞在虛擬語氣中的用法
情態動詞用於虛擬語氣中表示責備的感情色彩,用法如下:
(1)should have done表示“本來應該做某事而實際上未做”,而shouldn’t have done則表示“本不應該做某事而實際上做了”。如:
You should have told me about it earlier.
You shouldn’t have said such words to your parents.
(2)ought to have done也表示“本應該……”而ought not to have done則意為“本不應該……”。如:
You ought to have told me about it earlier.
You ought not to have said such words to your parents.
(3)needn’t have done表示“本無必要做某事而實際上做了”。如:
You needn’t have walked so quickly since time was enough.
(4)could have done表示“本來有可能……而事實上未做到”。如:
I could have come on time, but my car broke on the way.
二、精典名題導解
選擇填空
1. I was really anxious about you. You________home without a word.(NMET 2001)
n’t have ldn’t have left
dn’t have left n’t have
解析:答案為B。本題考查的是情態動詞在虛擬語氣中的用法。題目給出的條件是“我確實非常擔心你”,因此後面可知應是責備you不應該沒説一句話就離開了。
2.-Are you coming to Jeff’s party?
-I’m not sure. I__________ go to the concert instead.(NMET 2000)
d ld t
解析:答案為D。本題考查情態動詞的基本用法。由題目中“I’m not sure”,表明我可能去Jeff’s party,也可能去音樂會,故用might。
3. -Will you stay for lunch?
-Sorry, ____________. My brother is coming to see me.(NMET 99)
A.I mustn’t B.I can’t C.I needn’t D.I won’t
解析:答案為B。本題考查表示請求的英語口語,用will來向第二人稱提問的疑問結構,是表示一種請求和意願,是用疑問的形式來表達較為婉轉的祈使語氣,意思是“請你……,好嗎”,對於這種問句的肯定回答是:Suree! Gertainly! Yes, of course. I’d be glad to 等;否定回答通常是:I’m sorry, I can’t. No, I’m afraid I can’t. I’m sorry, but … I’d like to, but …等。注意情態動詞表客氣的用法及其在一般疑問句中的問與答。
三、專項訓練
1. -Jack certainly has a low opinion of Janny.
-It_______than hers of him.
’t be any worse be any worse
be some worse ’t be more worse
2. She_______be at home because she phoned me from her office just now.
n’t n’t ’t ldn’t
3. The big fire last night_______the whole the heavy rain helped.
t be burning down ld have been burned down
d have burned down have been burned down
4. I want to go to the dentist,but you_______with me.
not to go ’t need go not go go not
5. -Must we take a bus?
-No,you_______,You can walk from here.
not ’t have to ’t must ’t need
6. You_______return the book can keep it till next week if you like.
’t n’t not n’t
7. -Could I borrow your dictionary?
-Yes,of course you_______.
t ld
8. -May I stay here for another day?
-No,you_______.
n’t t not n’t ’t
9. -You ought to have helped her yesterday.
-Yes,I know I_______.
t to t to have
t have done t to have called
10. -_______he open the door?
-Yes,please.
l d
11. Whatever difficulties we_______with,we’ll go on with the experiment.
l meet meet
12. In the end they_______save the cat on the roof.
d able to
13. is in poor _______be ill at any time.
ld
14. -Could I see you on Sunday?
-Yes,of course you_______.
t ld
15. I thought you_______like something to read,so I have brought you some books.
d t
16. -Do you have to go out?
-Sorry,but I really_______.
to
17. “Manager,some people want to see you,_______they wait in the hall or outside?”asked the secretary.
l
18. There was plenty of time,she_______.
n’t have hurried n’t have hurried
hurried dn’t have hurried
19. You_______walk for miles and miles among the hills without meeting anyone.
ld
20. You_______do what you like to the whole afternoon.
d able to be able
21. Look,what you have done! You_______more careful.
be to ld be d be
22. Whoever breaks the law_______.
be punished to punish
to be punished punished
23. Don’t throw the box _______in the future.
l be needed needed t need t be needed
24. All that_______must be done.
ld be done done done been done
25. There_______an English evening next Saturday.
have going to be to have going to do
26. The news_______about everywhere now.
talking been talked
being talked being talking
27. We shall stay in the village for one or two days,and then we_______that mountain.
to climb on climbing
have climbed going to climb
28. Suddenly he thought that a bicycle_______be very useful.
d to ld
29. Johnny,you_______play with the knife,you_______hurt yourself.
’t;can’t n’t;may
ldn’t;must ’t;shouldn’t
30. Your phone number again? I_______quite catch it.
dn’t ’t ’t ’t
31. Come early tomorrow,_______?
’t you you l you you
32. Let’s go to see our teacher who is in hospital,_______?
l we you ’t we you
33. Everyone_______do his best to study well in order to sense the people well in future.
ld t
34. -May I stop here?
-No,you_______.
t not n’t n’t ’t
35. -Dare he go to the cinema in the evening?
-_______.
A.I dare too ,I don’t ,I do ,I daren’t
36. Don’t be news_______be true.
not n’t n’t ’t
37. I will return your notes as soon as I_______copying them.
finish finish sh finished
38. You_______do it even if you want to.
’t to n’t n’t
39. When_______possible to get some more information?
it it d be it d it be
40. He_______the test,but he wasn’t careful enough.
d have passed able to pass
t be able to pass have passed
參考答案
1-10 ACCCB DCABA 11-20 DBCAD BCADB
21-30 CCDAB CDABC 31-40 DABCD ACBDA